nixpkgs/pkgs/development/beam-modules/build-mix.nix

{
  stdenv,
  writeText,
  elixir,
  erlang,
  hex,
  lib,
}:

{
  name,
  version,
  src,
  buildInputs ? [ ],
  nativeBuildInputs ? [ ],
  erlangCompilerOptions ? [ ],
  # Deterministic Erlang builds remove full system paths from debug information
  # among other things to keep builds more reproducible. See their docs for more:
  # https://www.erlang.org/doc/man/compile
  erlangDeterministicBuilds ? true,
  beamDeps ? [ ],
  propagatedBuildInputs ? [ ],
  postPatch ? "",
  compilePorts ? false,
  meta ? { },
  enableDebugInfo ? false,
  mixEnv ? "prod",
  mixTarget ? "host",
  removeConfig ? true,
  # A config directory that is considered for all the dependencies of an app, typically in $src/config/
  # This was initially added, as some of Mobilizon's dependencies need to access the config at build time.
  appConfigPath ? null,
  ...
}@attrs:

assert appConfigPath != null -> removeConfig;

let
  shell =
    drv:
    stdenv.mkDerivation {
      name = "interactive-shell-${drv.name}";
      buildInputs = [ drv ];
    };

  pkg =
    self:
    stdenv.mkDerivation (
      attrs
      // {
        name = "${name}-${version}";
        inherit version src;

        MIX_ENV = mixEnv;
        MIX_TARGET = mixTarget;
        MIX_BUILD_PREFIX = (if mixTarget == "host" then "" else "${mixTarget}_") + "${mixEnv}";
        MIX_DEBUG = if enableDebugInfo then 1 else 0;
        HEX_OFFLINE = 1;

        ERL_COMPILER_OPTIONS =
          let
            options = erlangCompilerOptions ++ lib.optionals erlangDeterministicBuilds [ "deterministic" ];
          in
          "[${lib.concatStringsSep "," options}]";

        LANG = if stdenv.hostPlatform.isLinux then "C.UTF-8" else "C";
        LC_CTYPE = if stdenv.hostPlatform.isLinux then "C.UTF-8" else "UTF-8";

        # add to ERL_LIBS so other modules can find at runtime.
        # http://erlang.org/doc/man/code.html#code-path
        # Mix also searches the code path when compiling with the --no-deps-check flag
        setupHook = attrs.setupHook or writeText "setupHook.sh" ''
          addToSearchPath ERL_LIBS "$1/lib/erlang/lib"
        '';

        buildInputs = buildInputs ++ [ ];
        nativeBuildInputs = nativeBuildInputs ++ [
          elixir
          hex
        ];
        propagatedBuildInputs = propagatedBuildInputs ++ beamDeps;

        configurePhase =
          attrs.configurePhase or ''
            runHook preConfigure

            ${./mix-configure-hook.sh}
            ${lib.optionalString (removeConfig && isNull appConfigPath)
              # By default, we don't want to include whatever config a dependency brings; per
              # https://hexdocs.pm/elixir/main/Config.html, config is application specific.
              ''
                rm -rf config
                mkdir config
              ''
            }
            ${lib.optionalString (!isNull appConfigPath)
              # Some more tightly-coupled dependencies do depend on the config of the application
              # they're being built for.
              ''
                rm -rf config
                cp -r ${appConfigPath} config
              ''
            }

            runHook postConfigure
          '';

        buildPhase =
          attrs.buildPhase or ''
            runHook preBuild
            export HEX_HOME="$TEMPDIR/hex"
            export MIX_HOME="$TEMPDIR/mix"
            mix compile --no-deps-check
            runHook postBuild
          '';

        installPhase =
          attrs.installPhase or ''
            runHook preInstall

            # This uses the install path convention established by nixpkgs maintainers
            # for all beam packages. Changing this will break compatibility with other
            # builder functions like buildRebar3 and buildErlangMk.
            mkdir -p "$out/lib/erlang/lib/${name}-${version}"

            # Some packages like db_connection will use _build/shared instead of
            # honoring the $MIX_ENV variable.
            for reldir in _build/{$MIX_BUILD_PREFIX,shared}/lib/${name}/{src,ebin,priv,include} ; do
              if test -d $reldir ; then
                # Some builds produce symlinks (eg: phoenix priv dircetory). They must
                # be followed with -H flag.
                cp  -Hrt "$out/lib/erlang/lib/${name}-${version}" "$reldir"
              fi
            done

            # Copy the source so it can be used by dependent packages. For example,
            # phoenix applications need the source of phoenix and phoenix_html to
            # build javascript and css assets.
            mkdir -p $out/src
            cp -r "$src/." "$out/src"

            runHook postInstall
          '';

        # stripping does not have any effect on beam files
        # it is however needed for dependencies with NIFs like bcrypt for example
        dontStrip = false;

        passthru = {
          packageName = name;
          env = shell self;
          inherit beamDeps;
        };
      }
    );
in
lib.fix pkg